JP4483510B2 - A surface-coated cermet cutting tool that exhibits excellent chipping resistance with a hard coating layer in high-speed intermittent cutting - Google Patents

Description

  The present invention relates to a surface-coated cermet cutting tool (hereinafter referred to as a coated cermet tool) that exhibits excellent chipping resistance with a hard coating layer, particularly in high-speed intermittent cutting of steel or cast iron.

Conventionally, generally on the surface of a substrate (hereinafter collectively referred to as a tool substrate) composed of a tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet. ,
(A) Ti carbide (hereinafter referred to as TiC) layer, nitride (hereinafter also referred to as TiN) layer, carbonitride (hereinafter referred to as TiCN) layer formed by chemical vapor deposition of the lower layers. A Ti compound layer consisting of two or more of a carbon oxide (hereinafter referred to as TiCO) layer and a carbonitride oxide (hereinafter referred to as TiCNO) layer and having a total average layer thickness of 3 to 20 μm,
(B) an aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) layer having an average layer thickness of 1 to 15 μm, wherein the upper layer is formed by chemical vapor deposition;
A coated cermet tool formed by forming a hard coating layer composed of (a) and (b) above is known, and this coated cermet tool is used for continuous cutting and intermittent cutting of various steels and cast irons, for example. It is also known that
Japanese Unexamined Patent Publication No. 6-31503

In recent years, the performance of cutting machines has been remarkable. On the other hand, there is a strong demand for labor saving, energy saving, and cost reduction for cutting, and along with this, cutting has been on the trend of higher speed. For coated cermet tools, there is no problem when this is used for continuous cutting and interrupted cutting under normal conditions such as steel and cast iron. When it is used for high-speed intermittent cutting with repeated mechanical impacts at extremely short pitches, the hard coating layer that composes this is the high-temperature strength of the lower Ti compound layer and the high-temperature hardness of the upper Al ₂ O ₃ layer. However, since the high-temperature strength of the Ti compound layer is insufficient, it cannot respond satisfactorily to mechanical impacts. Since the ping (small chipping) tends to occur, at present, leading to a relatively short time service life.

In view of the above, the present inventors conducted research by paying attention to the Ti compound layer, which is the lower layer, in order to improve the chipping resistance of the hard coating layer of the above-described coated cermet tool. result,
Of the Ti compound layer that is the lower layer of the hard coating layer of the above coated cermet tool, the TiCN layer (hereinafter referred to as the conventional TiCN layer) is a normal chemical vapor deposition apparatus.
Reaction gas composition - by _{volume%, TiCl 4: 2~10%,} CH 3 CN: 0.5~3%, N 2: 10~30%, H 2: remainder,
Reaction atmosphere temperature: 800 to 900 ° C.
Reaction atmosphere pressure: 6-20 kPa,
However, prior to the formation of the conventional TiCN layer,
Reaction gas composition - by _{volume%, TiCl 4: 0.69 ~1%} , CH 4: 1~5%, H 2: 20~40%, N 2: 5~15%, Ar: the remaining,
Reaction atmosphere temperature: 780-820 ° C.
Reaction atmosphere pressure: 4-8 kPa,
Deposition time: 0.8 to 2.0 hours
The TiCN thin film as a seed thin film (hereinafter referred to as a TiCN seed thin film) is preferably formed with an average layer thickness of 0.8 to 1.2 μm under the above conditions, and the above-mentioned conventional TiCN layer is formed on the TiCN seed thin film. When the TiCN layer is formed under the same conditions, the TiCN layer at the time of formation is significantly affected by the crystal arrangement of the TiCN seed thin film, and the TiCN layer is formed as a result. (Hereinafter referred to as a history TiCN layer) has a higher high-temperature strength and superior mechanical impact resistance compared to the above-described conventional TiCN layer. The coated cermet tool in which the Al ₂ O ₃ layer and the lower layer are composed of the Ti compound layer and one of the Ti compound layers is the hysteresis TiCN layer is accompanied by particularly severe mechanical impact. Even in high-speed intermittent cutting, the hard coating layer exhibits excellent chipping resistance and exhibits excellent wear resistance over a long period of time.

(B) About the conventional TiCN layer and the history TiCN layer that constitute the lower layer of the hard coating layer of the above coated cermet tool,
Using a field emission scanning electron microscope, as shown in the schematic explanatory diagrams of FIGS. 1A and 1B, electron beams are individually applied to crystal grains having a cubic crystal lattice existing within the measurement range of the surface polished surface. Irradiate and use an electron backscatter diffraction image apparatus to measure the measurement range at an interval of 0.1 μm / step with respect to the normal of the surface polished surface of the {013} plane that is the crystal plane of the crystal grain The inclination angle formed by the normal line is measured, and among the measurement inclination angles, the measurement inclination angle within the range of 0 to 45 degrees is divided for each pitch of 0.25 degrees, and the frequency existing in each division is determined. In the case of creating the aggregated inclination angle number distribution graph, the conventional TiCN layer is unbiased in the range of the measured inclination angle of the {013} plane within the range of 0 to 45 degrees as illustrated in FIG. While the tilt angle number distribution graph is shown, the history TiCN layer is shown in FIG. As illustrated, a sharp maximum peak appears at a specific position in the tilt angle section, and the sharp maximum peak has a height that appears in the tilt angle section on the horizontal axis of the graph, and the reaction atmosphere temperature and reaction during the formation of the TiCN seed thin film. It changes according to the atmospheric pressure, and the inclination angle division position on the horizontal axis of the graph also changes depending on the TiCl ₄ content of the reaction gas.

(C) As described above, when the TiCN seed thin film is formed, by setting the content of TiCl _{4 in} the reaction gas to 0.69 to 1%, the gradient angle number distribution graph of the history TiCN layer has a sharp maximum. The peak appears in the range of 20.00 to 24.25 degrees of the tilt angle section, and the reaction atmosphere temperature is 780 to 820 ° C. and the reaction atmosphere pressure is 4 to 8 kPa, so that the peak is within the range of 20 to 30 degrees. In the inclination angle distribution graph, the total of the frequencies existing in the inclination angle section occupies a ratio of 62 to 83 % of the entire frequency in the inclination angle distribution graph. In this case, according to the test result, When the content of TiCl ₄ is less than 0.69%, at an inclined angle frequency distribution graph of the history TiCN layer, it appears at a position where the inclination angle division position of the highest peak exceeds 24.25 degrees Uninari, while its content is in a position lower than the inclined angle division position of the highest peak in the opposite 20 degrees exceeds 1%, With respect to the reaction atmosphere temperature and reaction atmosphere pressure, temperature becomes lower than 780 ° C. When the pressure is less than 4 kPa, the frequency ratio existing in the tilt angle section in the range of 20 to 30 degrees in the tilt angle distribution graph of the hysteresis TiCN layer becomes too high exceeding 83 %, and the high temperature hard On the other hand, if the temperature exceeds 820 ° C. or the pressure exceeds 8 kPa, the power ratio will be less than 62 %, and the desired excellent high-temperature strength can be ensured. Things impossible.
The research results shown in (a) to (c) above were obtained.

The present invention has been made based on the above research results, and on the surface of a tool base composed of a WC-based cemented carbide or TiCN-based cermet,
(A) The lower layer is composed of two or more of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer, all formed by chemical vapor deposition, and has a total average layer thickness of 3 to 20 μm. Ti compound layer,
(B) Al ₂ O ₃ layer having an average layer thickness of 1 to 15 μm, wherein the upper layer is formed by chemical vapor deposition,
In the cutting tool made of surface-coated cermet formed by forming the hard coating layer composed of (a) and (b) above,
One layer of the Ti compound layer of the above (a),
Reaction gas composition - by _{volume%, TiCl 4: 0.69~1%,} CH 4: 1~5%, H 2: 20~40%, N 2: 5~15%, Ar: the remaining,
Reaction atmosphere temperature: 780-820 ° C.
Reaction atmosphere pressure: 4-8 kPa,
Deposition time: 0.8 to 2.0 hours
Under the conditions, through a TiCN seed thin film formed by chemical vapor deposition to an average layer thickness of 0.8 to 1.2 μm,
Reaction gas composition - by _{volume%, TiCl 4: 2~10%,} CH 3 CN: 0.5~3%, N 2: 10~30%, H 2: remainder,
Reaction atmosphere temperature: 800 to 900 ° C.
Reaction atmosphere pressure: 6-20 kPa,
Under the conditions (corresponding to the conventional vapor deposition conditions), chemical vapor deposition with an average layer thickness of 2.5 to 15 μm ,
Using a field emission scanning electron microscope, each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the measurement range is set to 0 using an electron backscatter diffraction image apparatus. The inclination angle formed by the normal of the {013} plane, which is the crystal plane of the crystal grain, is measured with respect to the normal of the surface polished surface at an interval of 1 μm / step. In the inclination angle number distribution graph obtained by dividing the measured inclination angle within the range of ˜45 degrees into the pitches of 0.25 degrees and totaling the frequencies existing in each division, 20.00 to 24.25 The highest peak is present in the inclination angle section within the range of degrees, and the sum of the frequencies existing in the inclination angle section within the range of 20 to 30 degrees is a ratio of 62 to 83 % of the entire degrees in the inclination angle distribution graph. Shows the distribution graph of the number of inclination angles History TiCN layer,
It is characterized by a coated cermet tool that exhibits excellent chipping resistance with a hard coating layer in high-speed intermittent cutting.

Next, the reason why the constituent layers of the hard coating layer of the coated cermet tool of the present invention are numerically limited as described above will be described below.
(A) Ti compound layer (lower layer)
The Ti compound layer itself has high-temperature strength, and the presence of the Ti compound layer makes the hard coating layer have high-temperature strength, and firmly adheres to both the tool base and the upper Al ₂ O ₃ layer. Therefore, it has an effect of improving the adhesion of the hard coating layer to the tool base, but if the total average layer thickness is less than 3 μm, the above-mentioned effect cannot be sufficiently exhibited, while the total average layer thickness is If it exceeds 20 μm, it becomes easy to cause thermoplastic deformation particularly by high-speed intermittent cutting accompanied by generation of high heat, which causes uneven wear. Therefore, the total average layer thickness is set to 3 to 20 μm.

(B) History TiCN layer (lower layer)
As described above, when the TiCN seed thin film is formed, by setting the content of TiCl _{4 in} the reaction gas to 0.69 to 1%, the sharpest peak in the tilt angle number distribution graph is 20. The frequency which exists in the range of 20-30 degrees by appearing in the range of 00-24.25 degree | times , and setting the reaction atmosphere temperature to 780-820 degreeC and the reaction atmosphere pressure to 4-8 kPa. The hysteresis TiCN layer showing the inclination angle frequency distribution graph that occupies a ratio of 62 to 83% of the entire frequency in the inclination angle frequency distribution graph is formed, and as a result, the history TiCN layer has an excellent high temperature. However, if the average layer thickness is less than 2.5 μm, the desired excellent high-temperature strength cannot be provided in the hard coating layer, whereas the average If the thickness exceeds 15 [mu] m, easily heat the plastic deformation which causes partial wear is generated, since it becomes worn accelerates, determined the average layer thickness and 2.5～15Myuemu.

(C) Al ₂ O ₃ layer (upper layer)
The Al ₂ O ₃ layer has excellent high-temperature hardness and heat resistance, and contributes to improving the wear resistance of the hard coating layer. However, if the average layer thickness is less than 1 μm, the hard coating layer has sufficient wear resistance. On the other hand, if the average layer thickness exceeds 15 μm and becomes too thick, chipping tends to occur. Therefore, the average layer thickness is set to 1 to 15 μm.

  In addition, for the purpose of identification before and after the use of the cutting tool, a TiN layer having a golden color tone may be vapor-deposited as necessary, but the average layer thickness in this case may be 0.1 to 1 μm, This is because if the thickness is less than 0.1 μm, a sufficient discrimination effect cannot be obtained, while the discrimination effect by the TiN layer is sufficient with an average layer thickness of up to 1 μm.

  This invention-coated cermet tool has a high-temperature strength in which the hysteresis TiCN layer, which is one of the lower layers of the hard coating layer, is excellent even in high-speed intermittent cutting such as steel and cast iron with extremely high mechanical and thermal shock, Since it exhibits excellent chipping resistance, the hard coating layer exhibits excellent wear resistance without occurrence of chipping.

  Next, the coated cermet tool of the present invention will be specifically described with reference to examples.

As raw material powders, WC powder, TiC powder, ZrC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder, and Co powder all having an average particle diameter of 1 to 3 μm are prepared. Then, blended into the composition shown in Table 1, added with wax, ball mill mixed in acetone for 24 hours, dried under reduced pressure, and then press-molded into a green compact of a predetermined shape at a pressure of 98 MPa. Is vacuum-sintered at a predetermined temperature in the range of 1370 to 1470 ° C. for 1 hour in a vacuum of 5 Pa. After sintering, the cutting edge is subjected to honing of R: 0.07 mm. -Tool bases A, D, and E made of WC-base cemented carbide having a throwaway tip shape specified in CNMG120408 were manufactured.

Further, as raw material powders, TiCN (mass ratio TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, TaC powder, WC powder, Co powder, all having an average particle diameter of 0.5 to 2 μm. , And Ni powder, these raw material powders are blended in the blending composition shown in Table 2, wet mixed with a ball mill for 24 hours, dried, and then pressed into a compact at a pressure of 98 MPa. The powder is sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour, and after sintering, the cutting edge portion is subjected to a honing process of R: 0.07 mm to achieve ISO standard / CNMG120212. The tool bases b, c and e made of TiCN base cermet having the following chip shape were formed.

Next, on the surfaces of these tool bases A, D, E and tool bases b, c, e, a Ti chemical compound is used as a lower layer of the hard coating layer under the conditions shown in Table 3 using a normal chemical vapor deposition apparatus. forming a layer, this case, in forming the history TiCN layer of said Ti compound layer is first conditions shown in Table 4, i.e. seed film a~ against target history TiCN layer defined on the basis of the test results A TiCN seed thin film is formed under the conditions e , and subsequently, a history TiCN layer is deposited under the same conditions as the conventional TiCN layer formation conditions shown in Table 3 as described above, with the combinations and target layer thicknesses shown in Table 5. formed, then again under the conditions shown in Table 3, the present invention coated cermet tools by also in combination shown in Table 5, and to deposit formed at the target layer thickness of the Al ₂ O ₃ layer as an upper layer 1-6 It was produced, respectively.

For comparison purposes, as shown in Table 6, under the conditions shown in Table 3 as the lower and upper layers of the hard coating layer, the Ti compound layer and Al ₂ O having the target layer thickness shown in Table 6 are also used. Conventionally coated cermet tools 1 to 6 were respectively produced by vapor-depositing _three layers.

Next, with respect to the hysteresis TiCN layer and the conventional TiCN layer constituting the hard coating layer of the above-described coated cermet tool of the present invention and the conventional coated cermet tool, the number of tilt angles is measured using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus. Each distribution graph was created.
That is, the inclination angle number distribution graph is set in a lens barrel of a field emission scanning electron microscope in a state where the surfaces of the hysteresis TiCN layer and the conventional TiCN layer are polished surfaces, and 70 ° An electron backscatter diffraction image apparatus is used by irradiating an electron beam with an acceleration voltage of 15 kV at an incident angle with an irradiation current of 1 nA on each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface. , Measuring the inclination angle formed by the normal of the {013} plane, which is the crystal plane of the crystal grain, with respect to the normal of the polished surface at an interval of 0.1 μm / step in a region of 30 × 50 μm, Based on the measurement results, the measurement inclination angles within the range of 0 to 45 degrees out of the measurement inclination angles are divided for each pitch of 0.25 degrees, and the frequencies existing in each division are tabulated. Created by.

  In the graphs of slope angle distribution of various modified TiCN layers and conventional TiCN obtained as a result of this, the {013} plane exists in the slope section where the highest peak is present, and the slope section within the range of 20 to 30 degrees. Tables 5 and 6 show the ratios of the tilt angle numbers to the tilt angle number distribution graph as a whole.

In the above-mentioned various inclination angle number distribution graphs, as shown in Tables 5 and 6, the history TiCN layer of the coated cermet tool of the present invention has a distribution of measured inclination angles on the {013} plane of 20.00 to 24. An inclination angle number distribution graph in which the highest peak appears in the inclination angle section within the range of 25 degrees and the ratio of the inclination angle numbers existing in the inclination angle section within the range of 20 to 30 degrees is 62 to 83%. On the other hand, the conventional TiCN layer of the conventional coated cermet tool is unbiased within the range of 0 to 45 degrees of the measured inclination angle of the {013} plane, and there is no highest peak. The inclination angle number distribution graph in which the ratio of the inclination angle number existing in the inclination angle section within the range of 30 degrees is 30% or less was also shown.
FIG. 2 is a graph showing the inclination angle number distribution of the history TiCN layer of the coated cermet tool 4 of the present invention, and FIG. 3 is a graph showing the inclination angle number distribution graph of the conventional TiCN layer of the conventional coated cermet tool 4 .

Further, for the above-described coated cermet tools 1 to 6 and the conventional coated cermet tools 1 to 6 , the constituent layers of the hard coating layer were observed using an electron beam microanalyzer (EPMA) and an Auger spectroscopic analyzer (layer When the longitudinal section was observed), it was confirmed that both the former and the latter were composed of a Ti compound layer and an Al ₂ O ₃ layer having substantially the same composition as the target composition. Moreover, when the thickness of the constituent layer of the hard coating layer of these coated cermet tools was measured using a scanning electron microscope (same longitudinal section measurement), the average layer thickness (substantially the same as the target layer thickness) Average value of 5-point measurement) was shown.

Next, in the state where each of the above various coated cermet tools is screwed to the tip of the tool steel tool with a fixing jig, the present coated cermet tools 1 to 6 and the conventional coated cermet tools 1 to 6 are as follows:
Work material: JIS · SCM440 lengthwise equidistant 4 vertical grooved round bar,
Cutting speed: 360 m / min,
Incision: 1.5mm,
Feed: 0.20mm / rev,
Cutting time: minutes,
Dry high-speed intermittent cutting test (normal cutting speed is 220 m / min) of alloy steel under the above conditions (cutting condition A),
Work material: JIS / S50C lengthwise equal 4 round grooved round bars,
Cutting speed: 360 m / min,
Cutting depth: 2.0 mm
Feed: 0.25mm / rev,
Cutting time: 10 minutes,
Dry high-speed intermittent cutting test of carbon steel under the conditions (cutting condition B) (normal cutting speed is 250 m / min),
Work material: JIS / FCD450 lengthwise equidistant round bars with 4 vertical grooves,
Cutting speed: 360 m / min,
Cutting depth: 2.0 mm
Feed: 0.40mm / rev,
Cutting time: 10 minutes,
A dry high-speed intermittent cutting test (normal cutting speed is 220 m / min) of ductile cast iron under the above conditions (cutting condition C), and the flank wear width of the cutting edge was measured in any cutting test. The measurement results are shown in Table 7.

From the results shown in Tables 5 to 7, in the coated cermet tools 1 to 6 of the present invention, one of the lower layers of the hard coating layer has an inclination angle of {013} plane of 20.00 to 24.25. In the history TiCN layer showing an inclination angle distribution graph showing the highest peak in the inclination angle section within the range of degrees and the total ratio of the frequencies existing in the inclination angle section range of 20 to 30 degrees occupying 62 to 83 % Even in high-speed intermittent cutting of steel and cast iron that are configured and have extremely high mechanical impact, the hysteresis TiCN layer has excellent high-temperature strength and excellent chipping resistance, so chipping at the cutting edge is extremely significant. In contrast to being suppressed and exhibiting excellent wear resistance, one of the lower layers of the hard coating layer has an unbiased distribution of measured inclination angles on the {013} plane within the range of 0 to 45 degrees. , Tilt angle several minutes without the highest peak In the conventional coated cermet tools 1 to 6 composed of the conventional TiCN layer showing the fabric graph, the mechanical impact resistance of the hard coating layer is insufficient in high-speed intermittent cutting, so that the cutting edge portion has chipping. It is clear that it occurs and reaches the service life in a relatively short time.

  As described above, the coated cermet tool of the present invention has excellent chipping resistance not only in continuous cutting and intermittent cutting under normal conditions such as various steels and cast iron, but also in high-speed intermittent cutting that particularly requires high-temperature strength. Since it exhibits excellent cutting performance over a long period of time, it can sufficiently satisfactorily cope with higher performance of the cutting device, labor saving and energy saving of cutting, and lower cost.

It is a schematic explanatory drawing which shows the measurement range of the inclination angle of the {013} plane of the crystal grain in the various TiCN layers which comprise a hard coating layer. It is an inclination angle number distribution graph of the {013} plane of the hysteresis TiCN layer which constitutes the lower layer of the hard coating layer of the present coated cermet tool 4 . It is a gradient angle number distribution graph of the {013} plane of the conventional TiCN layer constituting the lower layer of the hard coating layer of the conventional coated cermet tool 4 .

Claims (1)

On the surface of the tool base composed of tungsten carbide based cemented carbide or titanium carbonitride based cermet,
(A) The lower layer is composed of two or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride layer, all formed by chemical vapor deposition, and 3 A Ti compound layer having a total average layer thickness of ˜20 μm,
(B) an aluminum oxide layer having an average layer thickness of 1 to 15 μm, wherein the upper layer is formed by chemical vapor deposition;
In the cutting tool made of surface-coated cermet formed by forming the hard coating layer composed of (a) and (b) above,
One layer of the Ti compound layer of the above (a),
Reaction gas composition - by _{volume%, TiCl 4: 0.69~1%,} CH 4: 1~5%, H 2: 20~40%, N 2: 5~15%, Ar: the remaining,
Reaction atmosphere temperature: 780-820 ° C.
Reaction atmosphere pressure: 4-8 kPa,
Deposition time: 0.8 to 2.0 hours
Under the conditions, through the titanium carbonitride thin film as a seed thin film formed by chemical vapor deposition to an average layer thickness of 0.8 to 1.2 μm,
Reaction gas composition - by _{volume%, TiCl 4: 2~10%,} CH 3 CN: 0.5~3%, N 2: 10~30%, H 2: remainder,
Reaction atmosphere temperature: 800 to 900 ° C.
Reaction atmosphere pressure: 6-20 kPa,
Under the conditions (corresponding to the conventional vapor deposition conditions), chemical vapor deposition with an average layer thickness of 2.5 to 15 μm ,
Using a field emission scanning electron microscope, each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the measurement range is set to 0 using an electron backscatter diffraction image apparatus. The inclination angle formed by the normal of the {013} plane, which is the crystal plane of the crystal grain, is measured with respect to the normal of the surface polished surface at an interval of 1 μm / step. In the inclination angle number distribution graph obtained by dividing the measured inclination angle within the range of ˜45 degrees into the pitches of 0.25 degrees and totaling the frequencies existing in each division, 20.00 to 24.25 The highest peak is present in the inclination angle section within the range of degrees, and the sum of the frequencies existing in the inclination angle section within the range of 20 to 30 degrees is a ratio of 62 to 83 % of the entire degrees in the inclination angle distribution graph. Shows the distribution graph of the number of inclination angles Titanium carbonitride layer,
A surface-coated cermet cutting tool that exhibits excellent chipping resistance with a high hard coating layer in high-speed intermittent cutting.

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